Improvement in step-ladders



UNITED STATES PATENT OFFICE.

CHARLES FRIZELL, OF BOSTON, MASSACHUSETTS.

IMPROVEMENT IN STEP-LADDERS.

Specification forming part of Letters Patent No. 140,578, vdated July 8,1873 5 application filed May 29, 1873.

-tie-rods'which unite the same, by which the sides are greatlystrengthened, Without materially increasing their weight.

The accompanying drawing represents a side elevation of the ladder withthis improvement applied.

In the drawing, a a are the string-pieces,

and b b are the tie-rods, the end of which are, respectively, secured inbars a. c c are short pieces which serve to unite the respective eX-tremities of bars a, and form a broader bearing. d d are diagonal bracesor rods, which are secured in bars a, as shown, and which serve asstays, by which the compressive strain upon the upper and the tensilestrain upon the lower bar are economized Vfor their reciprocal support.

What I cla-im as my invention is- The diagonal rods d, in combinationwith bars a a and tie-rods b, substantially as and for the purposesspecified.

CHARLES FRIZELL.

Witnesses:

EBEN HU'rcHINsoN, T. W. PORTER.

